Perceptual grouping is well-known to be a fundamental process during visual perception, notably grouping across scenic regions that do not receive contrastive visual inputs. Illusory contours are a classical example of such groupings. Recent psychophysical and neurophysiological evidence have shown that the grouping process can facilitate rapid synchronization of the cells that are bound together by the grouping, even when the grouping must be completed across regions that receive no contrastive inputs. Neural models of perceptual grouping have clarified how such fast synchronization may occur (Grossberg and Somers, 1991; Grossberg and Grunewald, 1997) by using bipole grouping cells (Cohen and Grossberg, 1984; Grossberg and Mingolla, 1985), whose predicted properties have been supported by later anatomical, psychophysical and neurophysiological experiments (Bosking et al. 1997, Callaway and Wiser, 1996; Eckhorn et al., 1988; Field et al., 1993; Fitzpatrick et al., 1985; Gilbert and Wiesel 1989; Gray et al., 1989; Shipley and Kellman, 1991; von der Heydt et al., 1984).

These models have not, however, incorporated some of the realistic constraints on which groupings in the brain are conditioned, notably the measured spatial extent of long-range interactions in layer 2/3 of a grouping network, and realistic synaptic and axonal signaling delays. This work addresses the question: Can long-range interactions that obey the bipole constraint achieve fast synchronization under realistic anatomical and neurophysiological constraints that will initially desynchronize grouping signals? Our simulations show that the answer to this question is Yes.